Endoscope

ABSTRACT

A suction port is opened at the outer surface of a distal end section of an endoscope and a valve member is located within the suction port. The valve member is adapted to be moved from a first position in which the suction port is fully opened, to a second position in which the suction port is restricted in its opening area. In the first position of the valve member, a body liquid or liquid substance present within the body organ of a patient is suctioned through the suction port. In the second position of the valve member, the suction port is opened substantially along a view window, whereby the liquid substance deposited onto a view window can be removed.

D United States Patent 1191 [111 3,

Mitsui Dec. 9, 1975 ENDOSCOPE 3,726,272 4/1973 Fukami et a1 128/6Inventor: Kazuhiko Mitsui, y pan 3,835,842 9/1974 Iglesias 128/7 FOREIGNPATENTS OR APPLICATIONS [73] Asslgneez Olympus Optical Company, Ltd.,128 6 Tokyo, p 1,964,603 7/1970 Germany [22] Filed: May 22, 1974 .OTHERPUBLICATIONS Med1ca1-Surg1cal Review (Advertisement), Flrst [21] Appl.No.: 472,343 Quarter, 1969.

o e gn pp cat on ata ExaminerKyle Howell May 23, 1973 Japan 48-60530[U]May 23, 1973 Japan 48-60531[U] May 23, 1973 Japan 48-60532[U] A sumo POpened at the outer Surface of a tal end section of an endoscope and avalve member 1s 52 us. c1 128/2 B; 128/6; 356/241 Within the Swim ff sis 51 1m. (:1. A61B 1/06 adapted to from a fi hi 3 58 Field Of Search128/6-8, 3, aff g gP gg.12 3F 9? 52212 1282B,1l,303.l;3269'3 41 e u mSOPI l 56/2 In the first position of the valve member, a body liquid [561CM 3:3231523232521111211?:12"$2,231,513:ii: UNITED STATES PATENTS secondposition of the valve member, the suction port 944,830 12/1909 Sussman128/ 3 is ope d bstantially along a iew window, whereby w 1 g the liquidsubstance deposited onto a view window arr1ner.... 3,164,904 l/1965Barnes 32/69 can be removed. 3,561,432 2/1971 Yamaki et a1. 128/6 6Claims, 17 Drawing Figures US. Patent Dec. 9, 1975 Sheet 1 of 53,924,608

US. Patent Dec. 9, 1975 Sheet 2 of5 3,924,608

U.S. Patent Dec. 9, 1975 Sheet 3 of 5 3,924,608

US. Patent Dec. 9, 1975 Sheet4 0f5 3,924,608

US. Patent Dec. 9, 1975 Sheet 5 of5 3,924,608

FIG. 16

ENDOSCOPE BACKGROUND OF THE INVENTION This invention relates toendoscope and more particularly to an improvement in the distal endsection of the endoscope.

Difficulties are presented when the body cavity or body organ isvisually observed, or photographed, through a view window of anendoscope i.e. through a view window leading through objective lenses toan image guiding fiber bundle and then to an eyepiece. That is, a fieldof view is often shut out, because a body fluid or fluid substancepresent within the body organ of a patient is deposited onto the outersurface of the view window. For this reason, the affected portion of thebody organ or body cavity has not been fully observed or clearlyphotographed.

With the conventional endoscope, a suction port is provided at the outersurface of its distal end section and a body liquid or liquid substanceis suctioned through the suction port into the-interior of theendoscope.

Since, however, the suction port is provided on the same plane as theouter surface of the distal end section, a suction force is directed ina direction substantially perpendicular to the outer surface of thedistal end section of the endoscope and a suction force does not workdirectly on a body fluid or fluid substance deposited onto the outersurface of the view window. It is therefore impossible to remove theliquid substance relatively firmly deposited onto the outer surface ofthe view window.

SUMMARY OF THE INVENTION It is accordingly the general object of thisinvention to provide an endoscope of the type in which a valve member islocated within the distal end section thereof and the valve member isadapted to be moved from one position to the other position to cause asuction port to be opened substantially along the outer surface of thedistal end section, causing a body fluid or liquid substance to beflowed along the outer surface of the distal end section, whileimparting a suction force directly to the liquid substance depositedonto a view window, to permit the deposited liquid substance to beremoved from the view window.

According to one embodiment of this invention, a valve member is locatedwithin a suction port and adapted to be swung from a first position inwhich a suction port is fully opened, to a second position in which thesuction port is restricted in its opening area. In the second positionof the valve member the suction port is caused to be openedsubstantially along a view window. Where a forceps is inserted into asuction channel, the valve member acts as a forceps raising member forcontrolling the direction in which the tip of the forceps extends.

According to another embodiment of this invention a valve member is madeof a flexible material and located within the distal end section of theendoscope in a manner to be slidably movable in the neighborhood of asuction port. The valve member is slidably moved from a first positionin which the suction port is fully opened, to a second position in whichthe suction port is restricted in its opening area. In the secondposition of the valve member the suction port is caused to be openedalong a view window and a suction force acts directly on a body fluid orfluid substance deposited onto the view window and the depositedsubstance is rapidly removed under an increased suction force from theview window. The valve member serves as a forceps raising member.

With an endoscope according to a further embodiment of this invention, alarge-mouthed main suction port and an auxiliary suction port smaller inopening area than the main suction port are opened in the outer surfaceof a distal end section of the endoscope. The auxiliary suction portleading to an auxiliary suction channel communicates with a main suctionchannel leading to the main suction port. That is, the auxiliary suctionchannelis branched from the main channel. A valve member is locatedwithin the main suction port and is adapted to be swung from a firstposition in which the main suction port is fully opened, to a secondposition in which the main suction port is closed. In the secondposition of the valve member only the auxiliary port remains opened anda body fluid or fluid substance is suctioned through the auxiliary portinto the auxiliary suction channel. Since the auxiliary suction port isopened along a view window, a suction force acts directly on a fluidsubstance deposited onto the view window and the deposited fluidsubstance is rapidly suctioned under an increased suction force into theendoscope. The advantages of this embodiment reside in that theauxiliary port can be easily provided in proximity to the view windowand that a suction device needs only to be connected to the main suctionchannel, since the auxiliary suction port leading to the auxiliarysuction channel communicates with the main suction channel.

A primary object of this invention is to provide an endoscope equippedwith an improved distal end section capable of rapidly removing, underan increased suction force, any body liquid or fluid substance depositedonto a view window.

A second object of this invention is to provide an endoscope equippedwith an improved distal end section capable of removing any body liquidor fluid substance deposited onto the view window, without involving anycomplicated construction or operational difficulty.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end view of the distalend section of an endoscope according to a first embodiment of thisinvention;

FIG. 2 is a perspective view of the distal end section of FIG. 1;

FIG. 3 is a perspective view of a valve member provided at the distalend section. of FIG. 1;

FIG. 4 is a sectional side view showing the distal end section of FIG.1;

FIG. 5 is a sectional side view of the distal end section of FIG. 1 inwhich the valve member is in a raised position;

FIG. 6 is a sectional side view of the distal end section of FIG. 1, inwhich a forceps is inserted through a suction channel;

FIG. 7 is a sectional side view of a proximal end of an endoscopeaccording to the first embodiment of this invention;

FIG. 8 is a perspective view showing the distal end section of anendoscope according to a second embodiment of this invention;

FIG. 9 is a perspective view of a valve member provided at the distalend section of FIG. 8;

FIG. 10 is a sectional side view of the distal end section of FIG. 8;

FIG. 11 is a sectional side view of the distal end section of FIG. 10,in which the valve member is in a shifted position;

FIG. 12 is an end view showing the distal end section of an endoscopeaccording to a third embodiment of this invention;

FIG. 13 is a perspective view showing a valve member provided at thedistal end section of FIG. 12;

FIG. 14 is a sectional side view of the distal end section shown in FIG.12;

FIG. 15 is a sectional side view of the distal end section of FIG. 12,in which the valve member is in a closed position;

FIG. 16 is a sectional side view of the distal end section of FIG. 12,in which a forceps is inserted through a suction channel; and

FIG. 17 is a sectional side view of the distal end section of anendoscope according to a fourth embodiment of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 7 show a firstembodiment of an endoscope according to this invention. FIG. 1 shows anouter end surface 2 of a distal end section 1 of the endoscope. Theendoscope is of a forward view type and has a view window 4 at the endsurface 2 of the endoscope. The view window 4 is defined by a windowopening 5 and a transparent cover glass constituting the view window isfitted to the opening 5. An outer surface 4a of the view window 4 isplaced on the same plane as the end surface 2 of the distal end section.Objective lenses 3 constitute an image guide means, together with afiber bundle 6 and an eyepiece 8 provided in a control unit 7 which islocated at the proximal end of the endoscope. An observer can observe abody cavity or body organ -hereinafter referred to merely as a bodyorgan through the view window leading to the image guide means. A pairof illumination windows 9 are provided one on the right side of the viewwindow 4 and one on the left side thereof. A light source, not shown, isprovided, for example, at the control unit 7. A light from the lightsource is directed through fiber bundles to the illumination window 9 soas to illuminate the body organ. As shown in FIG. 1 a relativelywidemouthed suction port 10 having a predetermined opening area isprovided immediately below the view window 4. The suction port 10communicates with a suction channel 11 formed in the longitudinaldirection of the endoscope, and serves as means for receiving a bodyliquid or fluid substance from the body organ. The suction channel 11permits the body liquid to be passed up to the control unit 7. That is,a tube 12 having the suction channel 11 extends into the control unit 7of the endoscope and communicates with one end of a suction tube 14through a switching valve 13. The other end (not shown) of the suctiontube 14 extends outwardly of the endoscope and is connected to asuitable suction device. An operating button 15 with the switching valve13 can be manually depressed in a direction indicated by an arrow inFIG. 7. Upon depression of the operating button 15 the suction channel11 of the tube 12 communicates with the suction device through thesuction tube 14 and suction is effected. Upon release of the operatingbutton 15, communication with the suction device is cut off. Whensuction is effected, a body liquid within the body organ is suctionedfrom the suction port 10 into the suction channel 11 of the tube 12 anddischarged outside of the endoscope. Since the suction channel 11 has arelatively great inner diameter, the body liquid can be very rapidlysuctioned and discharged outside of the endoscope. Into the suctionchannel 11 a biopsy forceps 16 for treating the interior of the bodyorgan can be inserted, for example, as shown in FIG. 6. That is, thesuction channel 11 of the tube 12 can be utilized as a forceps channel.Where the forceps is inserted through the suction tube 12, the entry endof the suction tube 12 may be open to the exterior of the endoscopewithout being connected to the operating valve 13, through such aconstruction is not shown in the Figures.

A substantially rectangular projecting frame 17 is formed on the endsurface 2 of the distal end section in a manner to surround the suctionport 10. A cutout 18 is provided in that portion of the projecting frame17 which is closest to the view window 4.

Within the suction port 10 surrounded with the projecting frame 17 aplate-like valve member 19 is swingably supported. To the valve member19 one end of an operating wire 21 is fixed. The other end, not shown,of the wire 21 extends into the control unit 7 of the endoscope. Theother end of the wire 21 can be pulled or pushed by an operating meansprovided at the control unit 7. When the wire 21 is pulled, the valvemember 19 is swung about an axis 20 Le. from an open position shown inFIG. 4 to a restricted position shown in FIG. 5 where the suction port10 is restricted in its opening area. When the wire 21 is pushed, thevalve member 19 is returned to the open position. The extent of pullingor pushing the wire 21 can be adjusted. As a result, the angle throughwhich the valve member 19 is swung from the open position to therestricted position can be adjusted. When the forceps 16 is insertedthrough the suction channel 11 as shown in FIG. 6, the valve member 19is swung from the open position to the restricted position shown in FIG.6. The direction in which the tip of the forceps 16 extends can becontrolled by the swinging movement of the valve member 19. That is, thevalve member 19 acts as what is called a forceps raising member.

Generally, the endoscope comprises the distal end section 1, controlunit 7 disposed at the proximal end, and flexible tube 24 connecting thedistal end section 1 to the control unit 7. Though the flexible tube 24is partially shown in FIGS. 4 to 7, the construction and material of theflexible tube, per se, are known in the art. Within the flexible tube 24the fiber bundle 6 and suction tube 12 with the suction channel 11 arereceived along the longitudinal direction of the flexible tube 24. Letus explain the operation of an endoscope so constructed.

The distal end section 1 of the endoscope is inserted into a human bodyand the suction port 10 is fully opened by bringing the valve member 19into the open position. When suction is effected by the suction deviceprovided at the control unit 7, a body fluid or fluid substance issuctioned through the suction port 10 into the suction channel 11 anddischarged outside the endoscope. The interior of the body organ isobserved or photographed through the view window 4 leading to the imageguide means. Where the body liquid or fluid substance present within thebody organ of a patient is deposited onto the outer surface 4a of theview window 4 as shown in FIG. 5, it is necessary to remove it from theouter surface 4a of the view window 4. It is because that the field ofvision is shut out due to the presence of the fluid substance or bodyfluid and that it is impossible to fully observe the interior of thebody organ or sometimes it is impossible to make such an observation. Ifin such a case a photograph is taken, a blurred image is obtained or ina worst case no image is obtained. When suction is effected with thevalve member 19 in the open position, a fluid substance deposited ontothe view window 4 is suctioned in a direction indicated by arrows inFIG. 4. If, however, it is firmly deposited onto the view window 4, itcan not be removed from the view window 4. Since most of the fluidsubstance is suctioned in a direction substantially perpendicular to theouter surface 4a of the view window 4, the suction force does not workdirectly on the deposited fluid substance.

In such a case, the valve member 19 is swung, under the suction force,into the restricted position as shown in FIG. 5 to cause the suctionport to be opened substantially along the view window 4 to permit thefluid substance to be flowed along the view window 4 at an increasedspeed. In the restricted position of the valve member 4 the suction port10 is defined by the valve member 19, end surface 2, cutout l8 andprojecting frame 17, and the suction force acts directly on the fluidsubstance deposited onto the outer surface 421 of the view window 4 tocause it to be suctioned along the outer surface 4a of the view window 4as shown in FIG. 5. As a result, the fluid substance firmly depositedonto the outer surface 4a of the view window 4 can be easily removed.After the fluid substance is so removed, the interior of the body organis fully observed, or photographed, through the view window 4 led to theimage glide means. As a result, a clear-cut image of an affected portionof the body organ can be obtained.

FIGS. 8 to 11 show a second embodiment of an endoscope according to thisinvention. In the respective Figures, the construction of a distal endsection 30 to which this invention is directed is shown. In thisembodiment, a valve member 31 performing the similar function as thevalve member 19 of the first embodiment is provided. The valve member 31is slidably fitted to a curved slot 32 provided near a suction port 37.One end of the valve member 31 is connected to an operating wire 33.Upon pulling the wire 33 the valve member 31 is moved from a positionshown in FIG. 11 to a retracted position shown in FIG. 10 and, uponpushing the wire 33, it is moved from the retracted position to theposition shown in FIG. 11 where a suction port 37 is restricted in itsopening area. As will be understood from FIGS. 10 and 11 the valvemember 31 is made of a flexible material and can be flexibly and pliablybent when it is slid from one position to the other position.

A guide rail 34 is provided in each of a pair of projecting members 35.The guide rail 34 is curved in a manner to meet the curve of the slot 32and constitutes an extension of the curved slot 32. The pair ofprojecting members 35 are provided one at each side of the suction port37 i.e. one at the right side of the suction port and one at the leftside thereof. Consequently, the valve member 31 is guided along theright and left guide rails 34 and moved from the retracted position tothe restricted or shifted position. When the valve member 31 is moved tothe retracted position, the suction port 37 is in a fully opened state.Upon sliding the valve member 31 into the restricted or shiftedposition, the

suction port is restricted in its opening area. The restricted openingarea 38 is defined by the valve member 31, outer end surface 36 of thedistal end section, and the pair of projecting members 35. The suctionport 37 communicates with a suction channel 40 of a tube 39 and acts asmeans for receiving a body fluid or fluid substance. The suction channel40 is connected to a suction device provided in a control unit which isdisposed at the proximal end of the endoscope, and serves as means forpassing the body fluid therethrough.

Above the projecting member 35, a view window 41 made of a cover glassis fitted to an opening 42 provided in the end surface 36 of a distalend section 30. Into a bore provided at the back of the window 41,objective lenses 43 and fiber bundle 44 are provided as in the case ofthe first embodiment. The outer surface 412 of the view window 41 isplaced on the same plane as the end surface 36 of the distal end section30. A pair of illumination windows 45 are provided one at each side ofthe view window 41 as in the case of the first embodiment. In thisembodiment, the control unit disposed at the proximal end of theendoscope is omitted and a flexible tube 47 is partially shown.

Let us now explain how the interior of the body organ in observed andhow a body liquid is discharged outside of the endoscope.

The valve member 31 is pulled by the wire 33 into the retracted positionwhere the suction port 37 is in a fully opened state. Under theinfluence of the suction device a body liquid or fluid substance issuctioned through the suction port 37 into a suction channel 40 as shownin FIG. 10. At this time, the body liquid is flowed in a directionsubstantially perpendicular to the outer surface 36 of the distal endsection as shown by arrows in FIG. 10. Where the fluid substance isfirmly deposited onto the view window 41, no sufficient suction forcecan be imparted to the fluid substance in an attempt to suction thefluid substance into the suction port 37. In such a case, the wire 33 ispushed to cause the valve member 31 to be moved from the retractedposition to the position shown in FIG. 11, where the suction port 37 isrestricted in its opening area. When the suction port 37 is sorestricted, the fluid substance is suctioned, at an increased speed,along the end surface 36 of the outer and into the suction port throughthe restricted opening area 38, since a suction force acts directly onthe fluid substance. As a result, the interior of the body organ can befully observed, or photographed, through the view window 41 leading tothe object lens 43, fiber bundle 44 etc. As a result, a clear-cut imageof the affected portion of the body organ can be obtained.

The suction channel 40 has a relatively large opening area to permit afair amount of body liquid to be passed therethrough at rapid speed, andit can also be utilized as a channel for a forceps as in the firstembodiment. The valve member 31 can act as a forceps raising member.

FIGS. 12 to 16 show a third embodiment of an endoscope according to thisinvention. In these Figures the construction of a distal end section 50of the endoscope is shown. In this embodiment a valve member 51 similarto those valve members shown in the first and second embodiments ismounted within a main suction port 52. The valve mem ber 51 is supportedin a manner to be swingable about an axis 53. The valve member 51 can beswung from a fully opened position shown in FIG. 14 to a closed positionshown in FIG. 15. As in the above-mentioned embodiments, the swingingmove- 7 ment of the valve member 51 can be effected by an operating wire54.

One end of the tube 55 having a main suction channel 56 communicateswith the main suction port 52. The other end, not shown, of the tube 55is connected, as in the above-mentioned embodiments, to a suction deviceprovided in a control unit which is located at the proximal end of theendoscope. The main suction channel 56 has a relatively large openingarea as in the above-mentioned embodiments and it is possible to inserta forceps 57 into the main suction channel 56 as shown in FIG. 16. Thatis, the main suction channel 56 can also be utilized as a forcepschannel.

Where the forceps 57 is inserted into the suction channel 56, the valvemember 51 can serve as a forceps raising member.

Short of one end of the tube 55 one end of a diameter-reduced tube 58 isopened and communicates with the main suction channel 56. The tube 58 isbypassed from the tube 55 and has a channel 59 constituting an auxiliarysuction channel. The other end of the tube 58 communicates with anauxiliary port 61. The auxiliary port 61 is defined by an outer endsurface 60 of the distal end section and a section 62 projecting aheadof the end surface 60. The port 61 is opened along an outer surface 63aof a view window 63. The view window 63 consisting of a cover glass iffitted to a window opening 64, and the outer surface 63a of the viewwindow lies on the same plane as the end surface 60 of the distal endsection. Into that bore of the distal end section 50 which is providedbehind the view window, objective lenses 65 and fiber bundle 66 arelocated as in the above-mentioned embodiments. A pair of illuminationwindows 67 are provided one at each side of the view window 63. Aflexible tube 69 is partially shown in FIGS. 14 to 16.

Let us now explain how the interior of the body organ is observed andhow a body liquid is discharged outside the endoscope.

The distal end 50 of the endoscope is inserted into the human body andthe main suction port 52 is fully opened by bringing the valve member 51into an open position. A body liquid present within a body organ issuctioned, under the suction force of the suction device, through themain suction port 52 into the main suction channel 56 as indicated byarrows in FIG. 14, while at the same time the body liquid is suctionedthrough the auxiliary port 61 into the auxiliary channel 59 and theninto the main channel 56. In this case, the amount of body liquid passedthrough the port 61 will be much smaller than the amount of body liquidpassed through the main port 52.

Suppose that a fluid substance is deposited onto the outer surface 63aof the view window 63 as shown in FIG. 14. Where such fluid substance isremoved from the outer surface 63a of the view window 63, the valvemember 51 is swung into a closed position as shown in FIG. 15, where themain suction port 52 is closed and only the auxiliary port 61 remainsopened. This means that an imaginary suction port having an opening areacorresponding to a summed opening area provided by both the main andauxiliary suction ports 52 and 61 is restricted to the opening area ofthe auxiliary suction port 61. As a result, the body fluid or fluidsubstance is suctioned, under an increased suction force and atincreased speed, through the auxiliary port 61 into the auxiliarysuction channel 59. At this time, the fluid substance is flowed alongthe end surface 60 of the endo- 8 scope as shown in FIG. 15. Since thesuction force acts directly on the fluid substance deposited onto theouter surface 63a of the view window 63, any deposited fluid substancecan be removed from the view window 63.

In this embodiment the tube 58 is disposed within the distal end sectionof the endoscope in a manner to cross the fiber bundle 66 withoutinterference.

FIG. 17 shows a fourth embodiment of the endoscope according to thisinvention. The above-mentioned three embodiments are all directed towhat is called a forward view type endoscope. However, the invention canalso be applied to what is called a side view type endoscope. The fourthembodiment is directed to a side view type endoscope having main andauxiliary suction channels as in the third embodiment.

A main suction port 72 is opened into an outer side surface 71 of adistal end section of the endoscope. The main suction port 72communicates with a substantially L-shaped main suction channel 73provided in the distal end section 70 of the endoscope. A valve member74 similar to the valve member 51 of the third embodiment is swingablymounted within the main suction port 72. The valve member 74 can beswung from an open position as shown in a solid line to a closedposition as shown in a broken line. An auxiliary suction channel 75 isbranched from the main suction channel 73 and has a smaller opening areathan the main suction channel 73. The auxiliary suction channel 75 leadsto an auxiliary port 76 which opens along an outer surface 77a of a viewwindow 77. The view window 77 consisting of a cover glass is fitted to awindow opening 78 provided in that side surface 71 of the distal endsection 70 which is in close proximity to the auxiliary port 76. Theouter surface 77a of the view window 77 is flush with the side surface71 of the distal end section. Immediately below the view window 77 islocated a prism 79 which leads to an image guide means such as objectivelenses 80, fiber bundle 81 etc. disposed within the distal end section70 of the endoscope.

When the interior of the human body is observed, the distal end section70 of the endoscope is inserted into a body organ and the valve member74 is brought into an open position. Under the suction force of asuction device a body liquid or fluid substance is rapidly suctioned ingreater amounts through the main suction port 72 to the main suctionchannel 73, while at the same time it is suctioned through the auxiliaryport 76. When any fluid substance 82 deposited onto the outer surface77a of the view window 77 is desired to be removed, the valve member 74is swung to a closed position to cause the main suction port 72 to beclosed. This permits the fluid substance to be suctioned under anincreased suction force and an increased speed. Since the auxiliary port76 is defined by a projecting waL3 and side surface 71 of the distal endsection and opened along the outer surface 77a of the view window 77,the fluid substance is flowed along the side surface 71 of the distalend section 70 and then along the outer surface 77a of the view window77 as indicated by arrows. In this case, a suction force is imparteddirectly to the fluid substance deposited onto the outer surface 77a ofthe view window 77 and the deposited fluid substance is easily suctionedthrough the port 76 into the auxiliary suction channel 75.

In this embodiment a forceps can be inserted into the main suctionchannel 73 and the valve member 74 can act as a forceps raising member,as in the above-mentioned embodiments. Though only the distal end sec- 9tion 70 of the endoscope is shown in this embodiment, it is needless tosay that the endoscope includes a control unit provided at the proximalend and a flexible tube connecting the control unit to the distal endsection.

It will easily occur to those skilled in the art that this invention canalso be applied to the other type endoscope, for example, an obliqueview type endoscope.

What is claimed is:

1. An endoscope to be inserted in the human body cavity including adistal end section having an outer surface provided with a view window,a control unit provided at the proximal end, and a flexible tubeconnecting said distal end section to said control unit, said endoscopefurther comprising:

port means formed in said distal end section so as to open at the outersurface, including a main suction port, and adapted to receive liquidsubstance from the body cavity under suction;

channel means including a forceps channel communicating with the mainsuction port of said port means and adapted to let the liquid substancepass therethrough from said port means; and

a valve member disposed in the main suction port of said port means andmade movable between an open position in which the opening area of themain suction port is fully open and a restricting position where itrestricts the opening area of the main suction port, said valve memberbeing positioned relative to said view window and said suction port suchthat when the valve member is moved to the restricting position, thedirection of flow of the liquid substance being taken into said portmeans under suction is changed to one substantially parallel to saidview window and the flow of the liquid substance is accelerated therebyre- 10 moving the liquid substance deposited on the view window.

2. An endoscope according to claim 1, in which said valve memberincludes means pivoting said valve member about an axis from the openposition to the restricting position thereof.

3. An endoscope according to claim 1, in which said valve member is madeof flexible material, retracted in a curved slot formed in said distalend section while resting at the open position, and shifted toward there stricting position slidably in said curved slot, and guided by aguide rail curving in conformity with said curved slot.

4. An endoscope according to claim 1, in which said port means includesan auxiliary suction port which opens in a direction parallel to theview window and which has an opening area smaller than that of said mainsuction port; said channel means including an auxiliary suction channelformed in said distal end section as to have one end communicating withsaid auxiliary suction port and the other end communicating with saidmain forceps channel; said main suction port and said auxiliary suctionport remaining respectively closed and opened while said valve memberrests in the restricting position.

5. An endoscope according to claim 4 in which said auxiliary suctionport is defined by the outer surface of the distal end section and asection projecting from the outer surface.

6. An endoscope according to claim 1, in which said valve member inintermediate positions, provides a forceps raising means for controllingthe direction of the tip of a forceps which is extended from the mainsuction port.

1. An endoscope to be inserted in the human body cavity including adistal end section having an outer surface provided with a view window,a control unit provided at the proximal end, and a flexible tubeconnecting said distal end section to said control unit, said endoscopefurther comprising: port means formed in said distal end section so asto open at the outer surface, including a main suction port, and adaptedto receive liquid substance from the body cavity under suction; channelmeans including a forceps channel communicating with the main suctionport of said port means and adapted to let the liquid substance passtherethrough from said port means; and a valve member disposed in themain suction port of said port means and made movable between an openposition in which the opening area of the main suction port is fullyopen and a restricting position where it restricts the opening area ofthe main suction port, said valve member being positioned relative tosaid view window and said suction port such that when the valve memberis moved to the restricting position, the direction of flow of theliquid substance being taken into said port means under suction ischanged to one substantially parallel to said view window and the flowof the liquid substance is accelerated thereby removing the liquidsubstance deposited on the view window.
 2. An endoscope according toclaim 1, in which said valve member includes means pivoting said valvemember about an axis from the open position to the restricting positionthereof.
 3. An endoscope according to claim 1, in which said valvemember is made of flexible material, retracted in a curved slot formedin said distal end section while resting at the open position, andshifted toward the restricting position slidably in said curved slot,and guided by a guide rail curving in conformity with said curved slot.4. An endoscope according to claim 1, in which said port means includesan auxiliary suction port which opens in a direction parallel to theview window and which has an opening area smaller than that of said mainsuction port; said channel means including an auxiliary suction channelformed in said distal end section as to have one end communicating withsaid auxiliary suction port and the other end communicating with saidmain forcepS channel; said main suction port and said auxiliary suctionport remaining respectively closed and opened while said valve memberrests in the restricting position.
 5. An endoscope according to claim 4in which said auxiliary suction port is defined by the outer surface ofthe distal end section and a section projecting from the outer surface.6. An endoscope according to claim 1, in which said valve member inintermediate positions, provides a forceps raising means for controllingthe direction of the tip of a forceps which is extended from the mainsuction port.